Fugitive coloring of yarns



Patented Jan. 18, 1944 FUGITIVE COLORINQ OF YARNS Paul Knapp, Waynesboro, Va., assignor to E. I. du Pont de Nemours & (lompany -Wilmington, Del., a corporation of Delaware No Drawing. Application August 11, 1941, Serial No. 406,405

2 Claims.

This invention relates to the fugitive coloring of filaments, yarns and threads of cellulose organic acid esters such as cellulose acetate.

By fugitive coloring or similar terminology used hereinafter is meant a coloration capable of substantially complete removal by a short treatment with warm dilute soap solution.

In the manufacture of certain textil products, different types of yarn are usedand it is desirable to differentiate and distinguish the various yarns in order to observe the fabric construction. Accordingly, one or more of the yarns going into the fabric are fugitively colored. Dyes forthis purpose are preferably of a water-soluble type which can be conveniently applied to the yarn from simple aqueous solution, and which can be readily removed from the yarn in the fabric by a moderate scouring operation without coloring or staining the other types of yarn in the fabric.

In the fugitive dyeing of cellulose acetate yarn, however, dyes which meet the preferred requirements above outlined generally do not yield satisfactory tints, and in the relatively few instances where the tints are satisfactory the fugitivity of the color is seldom all that could be desired. To cure this latter defect it has been proposed to dry the tinted yarn immediately after the application of th aqueous dye composition. However,

the fugitivity required is not always obtained by this treatment under the present conditions of high speed spinning where the yarn leaving the spinning cell contains a high percentage of solvent; for example, cellulose acetate yarn spun by the evaporative method from an acetone solution and wound up at a speed of600 yards or more per minute, may contain as much as 20% residual solvent. Coloring matter applied to this highly solvent-laden, and hence highly swollen, yarn frequently strikes in and in spite of immediate drying the yarn is sometimes more or less permanentlystained.

It is, therefore, an object of this invention to provide a dyestufl. which is eminently suited for the fugitive tinting of filaments, yarns and threads of organic acid esters of cellulose, such as cellulose acetate. Another object is o provide a dyestuif for the fugitive tinting of cellulose acetate which dyestuff can be easily applied to freshly. spun yarn from aqueous composition to distinctively tint the same, and which can be the cell by a suitable roll applicator.

These objects are realized by my invention which comprises applying, as the fugitive coloring material, an aqueous solution of Naphthol Green B (the ferric salt of l-nitro so-2-naphthol- 6-sodium sulfonate; Color Index No. 5) to freshly spun cellulose organic acid ester yarn.

Naphthol Green B is preferably applied at the spinning machine. to freshly formed cellulose acetate yarn to theextent of from 0.05% to 0.5% based on the air dry weight of the yarn. The yarn may b simultaneously tinted and finished by dissolving the dyestuif in a suitable aqueous finish emulsion containing the usual textile finishing agents such as olive oil, sulfonated olive oil, soap, polyhydric alcohol, mineral oil, etc., and applying the composition to the yarn as it leaves The tint may, however, be applied quite independently of the finish by contacting the yarn with a dilute aqueous solution of the same in any suitable manner.

Even though the yarn to which the dye is applied may, and'usually does, contain a very high concentration of solvent, such as 15 to 20% acetone, up to 0.5% of this dye (based on the air dry weight of the yarn) may be applied to freshly spun-cellulose acetate .yarn without resorting to any special procedure, for instance, such as immediately drying the yarn, a step heretofore considered essential to produce tinted yarn showing excellent fugitivity. This unusual high degree of fugitivity makes this dye outstanding for the fugitive tinting of cellulose acetate yarn before its initial windup. Although as much as 0.5% of the dye may be applied to the yarn, in general, for fugitively tinting yarn to be used in the manufacture of woven goods, substantially less thanthis amount is eminently satisfactory and from about 0.05% to 0.25% is preferred.

readily removed from the yarn by moderate scouring without noticeably coloring yarns of other types with which the cellulose acetate may be a sociated in a fabric. Other objects will I appear hereinafter.

' My invention is further illustrated by thefollowing example, wherein percentages are percentages by weight.

An aqueous tint finish solution is prepared of the following composition:

Cellulose acetate yarn dry spun from an acetone solution is passed over a rotating finish applicator roll, dipping in the emulsion contained in the suitable fihish troagh so as to apply to the yarn sufficient of the aqueous tint finish so that when the yarn is dried it will contain 1.5% to 4.0% of the non-volatile finish ingredients and in addition about 0.10% to 0.27% of the Naphthol Green dye. After contacting the finish applicator roll, the yarn is led over a takeup roll and onto a yarn package without any special attempt to dry the yarn, the windup being at the rate of about 600 yards per minute.

A mixed fabric is made comprising the cellulose acetate yarn so treated and viscose rayon yarn. The coloring matter in the cellulose acetate yarn is easily discharged by treating the fabric for ten minutes in an aqueous soap solution containing 0.2% sodium oleate and heated to a temperature of 70 C. Upon examination of the fabric, it will be noted that the celllulose ace- .tate yarn has completely discharged its color and that no staining of the viscose rayon yarn has occurred. Furthermore, the short time and low temperature discharge treatment has not materially affected the luster of the cellulose acetate yarn.

The very high degree of fugitivity of Naphthol is still wet with the aqueous tint finish, better cake formation is secured which makes subsequent handling and unwinding more eflicient with the final packaged yarn of improved quality. Since the aflinity of all types of yarn for this dye is extremely poor, it may be used as a fugitive color on cellulose acetate to be combined in fabrics with any other textile yarn without causing the other yarn to be undesirably stained 10 in the process of discharging the dye from the cellulose organic acid ester yarn.

It'is understood of course that my invention is not restricted to the exact conditions set out above for purposes of illustration, but compre- 15 hends all equivalents and modifications included in the spirit and terms of the following claims.

I claim:

1. Process for the fugitive coloring of filaments, yarns and threads of cellulose acetate 20 which comprises applying to the filaments, yarns and threads of cellulose acetate a solution consisting of Naphthol Green B and water.

2. Process for the fugitive coloring of filaments, yarns and threads of cellulose acetate 25 which comprises applying to filaments, yarns and threads of cellulose acetate'up to 0.5% by weight, based on the air dry weight of the cellulose acetate, of Naphthol Green B from aqueous com-- position wherein water is the sole solvent for said Naphthol Green B and comprises the major portion of said composition.

PAUL KNAPP. 

